全文获取类型
收费全文 | 1159篇 |
免费 | 142篇 |
国内免费 | 19篇 |
专业分类
电工技术 | 8篇 |
综合类 | 47篇 |
化学工业 | 40篇 |
金属工艺 | 16篇 |
机械仪表 | 71篇 |
建筑科学 | 11篇 |
矿业工程 | 7篇 |
能源动力 | 1篇 |
轻工业 | 829篇 |
水利工程 | 1篇 |
石油天然气 | 30篇 |
武器工业 | 27篇 |
无线电 | 29篇 |
一般工业技术 | 44篇 |
冶金工业 | 8篇 |
自动化技术 | 151篇 |
出版年
2024年 | 19篇 |
2023年 | 45篇 |
2022年 | 59篇 |
2021年 | 70篇 |
2020年 | 73篇 |
2019年 | 59篇 |
2018年 | 74篇 |
2017年 | 62篇 |
2016年 | 79篇 |
2015年 | 64篇 |
2014年 | 81篇 |
2013年 | 71篇 |
2012年 | 86篇 |
2011年 | 91篇 |
2010年 | 51篇 |
2009年 | 47篇 |
2008年 | 46篇 |
2007年 | 56篇 |
2006年 | 39篇 |
2005年 | 32篇 |
2004年 | 20篇 |
2003年 | 14篇 |
2002年 | 20篇 |
2001年 | 9篇 |
2000年 | 19篇 |
1999年 | 8篇 |
1998年 | 11篇 |
1997年 | 5篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1988年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有1320条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
鼻纹特征是当前最新研究的生物识别特征,对身份的鉴定有着重要的意义.鼻子的纹路较细小,只有在挤压过程中,才能留下纹理特征.但是,挤压过程本身对特征就形成了一定的破坏,使得特征扭曲变形,无法形成完整特征.传统的生物识别方法多是依靠完整生物特征,在鼻纹特征残缺或者挤压造成特征形变的情况下,虽然能识别出特征,但是对应过程会产生大量的干扰,造成假识别,漏识别的问题.提出采用鼻纹图像小区域分割的扭曲识别方法.针对扭曲鼻纹图像进行矩阵重组,根据重组结果进行分割,完成扭曲鼻纹图像的分类,利用自适应迭代出不同区域的识别阀值,设定识别过程中的最优阀值,最终完成扭曲鼻纹图像的识别.仿真结果表明,利用改进算法进行扭曲鼻纹图像识别,能够有效提高识别的准确率. 相似文献
5.
6.
灰色理论在电子鼻气体定量分析中的应用 总被引:1,自引:0,他引:1
将气体传感器阵列与灰色系统理论相结合,设计出用于气体定量分析的电子鼻。根据传感器数列得到的实验数据为基础数据建立了气体定量分析的灰色预测模型GM(1,N),并通过该模型对气体的体积分数进行了分析。实验证明:灰色系统理论用于气体的定量分析是可行的。 相似文献
7.
A novel humid electronic nose combined with an electronic tongue for assessing deterioration of wine 总被引:2,自引:0,他引:2
Luis Gil-SánchezAuthor Vitae Juan SotoAuthor Vitae Ramón Martínez-MáñezAuthor Vitae Eduardo Garcia-BreijoAuthor Vitae Javier IbáñezAuthor Vitae Eduard LlobetAuthor Vitae 《Sensors and actuators. A, Physical》2011,171(2):152-158
We report herein the use of a combined system for the analysis of the spoilage of wine when in contact with air. The system consists of a potentiometric electronic tongue and a humid electronic nose. The potentiometric electronic tongue was built with thick-film serigraphic techniques using commercially available resistances and conductors for hybrid electronic circuits; i.e. Ag, Au, Cu, Ru, AgCl, and C. The humid electronic nose was designed in order to detect vapours that emanate from the wine and are apprehended by a moist environment. The humid nose was constructed using a piece of thin cloth sewn, damped with distilled water, forming five hollows of the right size to introduce the electrodes. In this particular case four electrodes were used for the humid electronic nose: a glass electrode, aluminium (Al), graphite and platinum (Pt) wires and an Ag-AgCl reference electrode. The humid electronic nose together with the potentiometric electronic tongue were used for the evaluation of the evolution in the course of time of wine samples. Additionally to the analysis performed by the tongue and nose, the spoilage of the wines was followed via a simple determination of the titratable (total) acidity. 相似文献
8.
Quansheng ChenAuthor Vitae Jiewen ZhaoAuthor VitaeZhe ChenAuthor Vitae Hao LinAuthor VitaeDe-An ZhaoAuthor Vitae 《Sensors and actuators. B, Chemical》2011,159(1):294-300
Electronic nose (E-nose) technique was attempted to discriminate green tea quality instead of human panel test in this work. Four grades of green tea, which were classified by the human panel test, were attempted in the experiment. First, the E-nose system with eight metal oxide semiconductors gas sensors array was developed for data acquisition; then, the characteristic variables were extracted from the responses of the sensors; next, the principal components (PCs), as the input of the discrimination model, were extracted by principal component analysis (PCA); finally, three different linear or nonlinear classification tools, which were K-nearest neighbors (KNN), artificial neural network (ANN) and support vector machine (SVM), were compared in developing the discrimination model. The number of PCs and other model parameters were optimized by cross-validation. Experimental results showed that the performance of SVM model was superior to other models. The optimum SVM model was achieved when 4 PCs were included. The back discrimination rate was equal to 100% in the training set, and predictive discrimination rate was equal to 95% in the prediction set, respectively. The overall results demonstrated that E-nose technique with SVM classification tool could be successfully used in discrimination of green tea's quality, and SVM algorithm shows its superiority in solution to classification of green tea's quality using E-nose data. 相似文献
9.
10.
Preparation, characterisation and applications of thin films for gas sensors prepared by cheap chemical method 总被引:1,自引:0,他引:1
The physical properties of pure and doped (Ni, Os, Pd and Pt) SnO2 thin films, prepared by using a chloride-based inorganic sol–gel route, have been reported. These properties were investigated by using differential scanning calorimetry and thermogravimetric (DSC/TG), FTIR, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and atomic force microscopy (AFM) techniques. Microsensors for gas detection were also fabricated and tested in various atmospheres (nitrogen oxide, carbon monoxide, ethanol, methanol and methane). The dopants affected the coating properties depending on the formation of nanoparticles. Furthermore the gas-sensing properties towards reducing and oxidising gases were found to be dependent on the nature of doping element. An array consisting of the manufactured sensors has been arranged and examples of applications for “electronic nose” are given. 相似文献